1. Field of the Invention
The present invention relates to a tire noise reducing system, more particularly to a pneumatic tire suited for use in combination with a noise damper disposed in the tire cavity.
Noise generated from a tire rolling on a road surface is analyzed into many kinds of sound according to the causes and sources. For example, a resonance of air in the annular tire cavity causes so called road noise which sounds like “GHO” having a maximum power spectrum ranging from about 100 to 250 Hz.
2. Related Art
A noise damper made of a spongy material disposed in a tire cavity is well known in the tire art such a spongy material disposed in a tire cavity can damp the air resonance.
However, if the air resonance sound is effectively reduced, another kind of sound is relatively increased and becomes noise offensive to the ear specifically, so called pattern pitch noise around 200 Hz and so called “SHAH” sound over 1 kHz for which main cause is circumferentially repeated tread elements or grooves are increased on the whole.